The ability to bind molecules (e.g., proteins) and living cells to a substrate is essential to the operation of many devices and procedures in biotechnology. For example, some techniques for high-throughput screening of candidate drugs use microchips (e.g., pieces of silicon, or glass, typically having dimensions of no more than a few centimeters) that include living cells attached to a microchip surface. The living cells are contacted with a candidate drug, and the response of the cell to the candidate drug is measured, thereby indicating whether the candidate drug may be effective to modulate a biochemical or physiological pathway implicated in a disease state. The small size of the microchips permits many candidate drugs to be simultaneously screened.
Again by way of example, immunoassays can be conducted using microchips that include antibody molecules attached to a microchip surface. The microchip is contacted with a fluid sample taken from an animal subject (e.g., a human being), and binding of the cognate antigen to the antibody molecules immobilized on the microchip is measured. For example, unlabelled antibody A, that specifically binds to one portion of an antigen called antigen A, is attached to a surface of a microchip, and the microchip is contacted with a fluid sample (e.g., human blood sample) that includes an unknown amount of antigen A, under conditions that permit binding of antigen A to immobilized antibody A. The fluid sample is then washed away, and the microchip is contacted with fluorescently-labelled antibody B that binds to a different portion of antigen A than does antibody A. The amount of fluorescent antibody B bound to antigen A is measured, thereby permitting calculation of the amount of antigen A bound to the microchip. The amount of antigen A present in the fluid sample can therefore be calculated.
Consequently, there is a continuing need for microchips, and other devices, that selectively bind living cells, proteins, or other molecules, to one, or more, specific locations on a surface of the device, and methods for making such devices. Preferably, the devices can bind most, or all, types of living cells and/or proteins.